posix: handle newlocale() errors
posix: handle newlocale() errors

newlocale() will fail if the specified locale is not found. Here, it
can fail if the environment variables refer to an invalid or missing
locale.

Pointed-out-by: Casian Andrei <d69469640e26fa608d6a5c4508f133563451f4b8@gmail.com>

shyamalschandra/vlc,vlc-mirror/vlc,xkfz007/vlc,shyamalschandra/vlc,vlc-mirror/vlc,krichter722/vlc,xkfz007/vlc,xkfz007/vlc,krichter722/vlc,shyamalschandra/vlc,vlc-mirror/vlc,shyamalschandra/vlc,xkfz007/vlc,shyamalschandra/vlc,krichter722/vlc,xkfz007/vlc,vlc-mirror/vlc,krichter722/vlc,krichter722/vlc,shyamalschandra/vlc,vlc-mirror/vlc,xkfz007/vlc,xkfz007/vlc,vlc-mirror/vlc,shyamalschandra/vlc,vlc-mirror/vlc,krichter722/vlc,krichter722/vlc